The need for storage is growing at an exponential rate, fueled by multimedia requirement for text, images, video and audio information. In order to meet this need storage systems include many diverse technologies, for example, magnetic disk drives, magnetic tape drives and tape libraries, optical disk drives and optical libraries.
Optical storage systems and devices, for example, compact disc (CD) and digital versatile disc (DVD), provide high storage capacity and low media cost. These qualities make optical storage devices attractive for distribution of information, for example, copyrighted content or to backup data. An optical disk includes a plastic or glass substrate having one or more thin-film layers coated upon its surface(s). The information may be pre-recorded on the surface of the substrate by the disk manufacturer, or it may be recorded on one or more of the thin-film layers by the user. The available optical disks include, for example, compact disk audio (CD), compact disk read-only memory (CD-ROM), compact disk recordable (CD-R), CD-RW, DVD, DVD-R, DVD-RW, magneto-optical (MD), phase-change (PC) writable disks and write-once-read-many (WORM) media.
In certain types of optical disks some information, such as format marks and grooves, may be stamped onto the substrate itself, and then the substrate is coated with a storage layer that can be modified later by the user during recording of information. Typical storage layers are dye-polymer films for write-once application, tellurium alloys for ablative recording (also write-once), GeSbTe for phase-change rewritable media, and TbFeCo magnetic films for magneto-optical disks (also rewritable).
The availability of low cost CD and DVD writers has raised concerns of piracy and theft of secret data. Ideally, content providers and businesses could be protected from lost revenues due to illegal copying. Current US copyright laws allow users to make personal copies of content for backup and convenience. Various copy protection schemes have been devised to encode or encrypt the data stored on a disk to disable copying of content. Unfortunately, the existing copy protection schemes have been decoded since any personal computer (PC) can read the data stored on an optical disk and hackers learn to defeat the copy protection scheme. These schemes also violate copyright laws since often no legal copies are possible either.
In secure government, military and business applications optical disks can be a problem since large amounts of data can be mishandled or misappropriated on optical disks. Existing encryption schemes for data do not provide sufficient controls for secure data as many encryption schemes can be decoded or circumvented.
There thus remains a need for securing information stored on optical and/or magnetic media that cannot be decoded or circumvented by unauthorized users.